1. Field of the Invention
The present invention relates to space surveillance, and in particular to an apparatus and method for locally generating imaging data of the vicinity of a spacecraft, including the spacecraft itself.
2. Description of the Related Art
The deployment of satellites and other assets in space offer the ability to quickly survey vast geographical areas and to provide secure worldwide communications. Such assets are highly valuable in times of conflict, but also present high-value targets to opponents, and can be vulnerable to countermeasures.
Such countermeasures include a wide variety of anti-satellite (ASAT) threats such as direct-ascent kinematic weapons (some including decoys to prevent countermeasures), ground and space-based energy weapons such as lasers, and stealthy satellite ASATs that are deployed nearby or on the target satellite without being detected, where they remain until the attack commences and they are activated.
To address such threats, it is important that such threats be detected and identified. This mission category is known as Space Situational Awareness/Space Object Identification (SSA/SOI). A key component of this mission has to do with detecting, identifying, and keeping track of closely spaced objects (CSOs).
Currently, space surveillance is accomplished via the space surveillance network (SSN). This is a worldwide conglomeration of a number of ground based radars and optical sensors which provide data that is post processed to produce ephemeris data for each of the space objects. Because the SSN uses large, ground based sensors that can scan only limited portions of the sky at any given time and because the data is post processed using techniques that are manually intensive, the SSN is quite expensive to operate. As a high value target in times of conflict, it is also of questionable survivability.
Currently, there are well over 2000 cataloged space objects, ranging in size from that of a small bolt to that of a small car. If a collision between any of these objects and a spacecraft should occur, catastrophic failure of the spacecraft would be the likely result. Further, in a time of conflict, it is likely that the amount of space debris will increase, and the additional objects may well overwhelm the current SSN. Further, since the cataloged objects are sensed from long distances (e.g. from Earth) smaller objects, which can still cause damage to satellites, are not known or cataloged. CSO identification can be improved with the use of large optical telescopes having adaptive optics, but such telescopes are expensive, operationally time consuming, and are currently only effective in discriminating objects that are low Earth orbit (LEO). It is difficult to discriminate CSOs in mid to high Earth orbits (e.g. geostationary and geosynchronous), even with such telescopes. Perhaps worse, these current systems are even less capable of identifying threats that have actually attached themselves to the target satellite.
Recognizing these limitations, plans are underway to deploy a space based surveillance system (SBSS) to perform some or all of the functionality currently provided by the SSN. However, although the SBSS should be capable of performing some of the SSA/SOI mission, that system is inherently limited in its ability to discriminate and identify CSOs by the virtue of the distance of its sensors from the CSOs themselves.
Accordingly, there is a need to provide a surveillance system that can perform the SSA/SOI mission more accurately, more quickly, more survivably, and at lower cost. The present invention satisfies that need.